As it is known, additive manufacturing techniques involve the repetition of cycles, during which successive horizontal sections of the component to be made are formed. In particular, at the beginning of each cycle, a layer of powder is deposited by means of a dispenser, which is able to translate horizontally. This layer of powder has a substantially constant thickness and the powder has the same composition as the component to be made. After the layer of powder has been deposited, specific area thereof are melted through the scanning of a focused energy beam, typically a laser beam or an electron beam. In those areas where the powder is melted, a continuous, solid structure is formed, which defines a corresponding horizontal section of the component. These areas are selected by a control unit according to a mathematical model, which represents the geometry and the dimensions of the component to be made.
Once all the cycles have ended, the powder remaining around the component that has been formed is removed.
In the process described above, the powder is deposited on a support of the platform type, which is lowered in each cycles, after the melting step has ended, by a quantity equalling the thickness of the layer of powder deposited. In this way, the part of the component that has already been formed is lowered as well, so as to move on to the deposit step of the following cycle.
The powder deposited in the first cycle covers the entire platform, which hence defines the base of the entire volume of powder that is deposited in the different cycles. However, the final component obtained by this process occupies a very small part of said volume, for example 10%; therefore, a large quantity of powder is necessary for each component to be made.
Even though the residual powder is recovered, known solutions of the type described above are scarcely satisfactory, since the large quantity of powder needed leads to the use large containers for the storage thereof and to relative great amounts of time spent for the deposit steps carried out during the procedure.
Patent application US2009286007A1 relates to an additive manufacturing process, during which at least one barrier or containment wall is made, so as to define a confined working space where the powder remains enclosed. These barriers are formed in a progressive manner, layer by layer, just like the component being formed, by melting strips of powder through the same laser beam of the machine, as soon as the dispenser has deposited said powder.
However, this solution is not completely satisfactory either.
As a matter of fact, known dispensers let the powder fall through a horizontal slit with a fixed size, which depends on the specific application. With a slot having a fixed size, it is impossible for operators to adjust the dispensing of powder according to the working space. Indeed, US2009286007A1 shows a working space basically having a variable length, so that the part of the powder coming from the ends of the slit falls outside the working space, especially when the dispenser is located in the areas of the working space having a smaller length.
Therefore, even in this case, part of the deposited powder is actually unnecessary to carry out the process.